The purpose of this project is to examine the chemistry of L-asparaginase from several bacterial sources and to determine the role of specific amino acid residues in subunit interactions. The topics of present interest are: 1) The reaction of 2,4,6-trinitrobenzene sulfonic acid with amino acid side chains and subsequent treatment of the trinitrophenylated amino acids with borohydride; 2) Trinitrophenylation of L-asparaginase from Escherichia coli and Erwinia carotovora; 3) The effect of trinitrophenylation of intersubunit interactions; 4) The effect of borohydride treatment on intersubunit interactions in TNP-asparaginase.